suggestions on BBC Micro, voltage converter, PAL monitor (in US)?

From: Derek Peschel <dpeschel_at_eskimo.com>
Date: Mon Apr 22 19:26:26 2002

On Tue, Apr 23, 2002 at 12:57:32AM +0100, Tony Duell wrote:
> > It has been my mission for some time to bring a BBC Micro back from
>
> Darn good idea. IMHO the BBC micro is one of the best designed 8 bit
> machines out there. There are serveral models, though...
>
> I'd avoid the Model A (== Model B with chips missing). So many of the
> 'standard features' -- like the user port, ADC, and even 16K of the
> memory -- are not fited.

I was hoping for a Master (after I found out that most Model B games
run on it, I decided there were few disadvantages). A second processor
would be nice but I understand those are harder to find even in the UK.

> If you go for a Model B (32K RAM) (which is probably the easiest to find),
> try to get one with the disk interface chips fitted. The 8271 disk
> controller is almost impossible to get now, as are the kludgeboards
> containing a 1770 that some disk upgrades used.

Aren't disk systems with the 1771 (or maybe 1793) still easy to find?
And IIRC the Master usually has a 3.5" drive -- what controller chip
runs that?

There's also Econet but with one machine that's kind of pointless.

> There's also the B+ (64K RAM) and various versions of the Master series.
> Be warned that on these large sections of the logic are put into custom
> ULA chips (mind you, the Model A and B have 2 ULAs for serial and video).

"on these" = the B+ and Master? So which is the latest machine with
the smallest amount of custom logic?

> Alternatively, you could use a step-up transformer (or even an
> autotransformer) and not modify the PSU at all. Some SMPSUs (and I think
> the BBC one is likely to be amongst them) will run happily on 300V _DC_
> input. You could use a couple of diodes and capacitors (say raided from
> an old PC power supply) to voltage-double your mains. But I guess if you
> knew how and why to do that, and how to check if the PSU could handle it,
> you'd not be asking about this :-)

I need to reread the thread to make sure I understand all the details.
Didn't I read that SMPSUs will generate their own 50Hz frequency? I don't
want to change the timing of the machine because then all the good games
probably wouldn't run.

> RGB. This is a 6 pin DIN socket carrying TTL-level R,G,B and composite
> sync. Realistically this is the one you should be using. If you've got an
> RGB monitor that can handle UK TV rates, then there _will_ be a way to
> hook it up.

I had forgotten (when I posted my original message) that RGB output was
available. So yes, that sounds like the easiest way.

> But it's probably simpler to find a monitor in the States that can handle
> UK rates (15625Hz horzontal, 50Hz vertical) with RGB inputs.

And that is what I was thinking. If the number of scan lines comes out
the same and all the colors come through (which they should) then there's
no need to ship a monitor back from England or run it on 240V.

> $500 for what? A BBC micro would be a lot less than that. So would a
> monitor (at least over here where every TV set can be used as an RGB
> monitor!). A step-up transformr of suitable power would be perhaps $50
> (but you don't need that if you can convert the PSU).

I was thinking $500 for a PAL composite monitor. Using RGB avoids that
expensive trap.

-- Derek
Received on Mon Apr 22 2002 - 19:26:26 BST